Orthodontic appliance



FIG. 1 is a top perspective view of an orthodontic appliance showing my new design;

FIG. 2 is a side elevational view thereof, the opposite side being substantially a mirror image of that shown;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a top plan view thereof; and

FIG. 6 is a bottom plan view thereof. 

The ornamental design for an orthodontic appliance, as shown and described. 